This invention relates to a peeling detector for a tunnel wall, which detects peeling of a wall of a tunnel while moving in the tunnel.
In inspecting a tunnel wall peeling, it has been customary practice to beat the wall surface manually with a hammer or the like, hear the sounds, and locate the site of peeling based on differences in sound.
Among methods for detecting the peeling of a concrete structure by use of infrared radiation is a method for detecting the difference in temperature between a peeled part and a normal part that occurs because of a change in the ambient temperature. This method has been used mainly in the inspection of a bridge footing or a building wall surface.
With the above-described hammering test of the tunnel wall, this wall is so wide that the sounding of the entire wall takes an enormous time.
The testing method using infrared rays poses the following problem: The interior of a tunnel is a closed space, and unlike a bridge footing or a building wall, is free from changes in the ambient temperature or exposure to sunlight throughout the day. In a natural condition, there is no difference in the wall temperature between the peeled part and normal part. Thus, the infrared (IR) method was not applicable to the inspection of the tunnel wall.